Aftertouch was fun for the first playthrough and until I got all the medal points for those levels on Hell mode, after that those levels got a bit boring and I havent replayed them at all. They are too long with too little happening. Still I liked the aftertouch but the level design for those sections doesnt work after you've played them through a couple times.
However the "tilt the controller upwards to perform an aerial combo" is still to this day the best use of sixaxis motion control in any game IMO, just perfect.
One thing I would've liked to be added to the game would've been one higher difficulty level after "Hell" where the enemies would take a lot more hits to kill (now all the fun ends way too quickly in every battle) and would be even more aggressive in their attacks against you.
Overall though I just love the game and it would be a huge shame if they never made a sequel for it.